Packets such as internet protocol (IP) packets can be broken into fragments for delivery across a network. For example, in an environment with multiple T-1 lines, the fragments can be distributed across several T-1 lines to be re-joined at a terminating device. Several devices currently take advantage of this technique by distributing fragments of packets on a round-robin basis among multiple T-1 lines. Typically, this delivery of fragments of packets occurs in a wireless packet data environment where there exists a packet data service node (PDSN), a radio network controller (RNC), and a base transceiver station (BTS).
One of the problems of delivering fragments of packets over multiple T-1 lines is that the fragments may arrive at their destination at different times causing a delay. For example, several fragments may take different routes to reach the same destination. As a result, some service providers have resorted to building in a delay scheme to allow fragments to “catch-up” with each other before finally delivering the re-joined packet to its final destination. Unfortunately, the built-in delay may not be enough time to allow the fragments to come together again. When this happens, the devices can drop the fragments resulting in a re-transmission of the fragments or the entire packet.
Another problem of delivering fragments of packets over multiple T-1 lines is that the fragments may arrive at their destination out of sequence. When this occurs, the entire packet is dropped since the device at the destination may not have enough intelligence to re-order the fragments. Typically, this action can occur with a data only module (DOM) that is found in a base transceiver station (BTS). Therefore, if a fragment arrives out of sequence at the DOM, the entire packet gets dropped.
Some service providers have resorted to implementing additional devices such as a load balancer into the network in order to handle the delay time to re-join fragments of packets or to keep packets from arriving at the DOM out of sequence. Several manufacturers make devices like the load balancer which includes the functionality of a router and algorithms. Such devices include the multi-link point-to-point protocol (MLPPP) by companies such as Cisco Systems of San Jose, Calif. and Juniper Networks, Inc. of Sunnyvale, Calif. Unfortunately, this implementation introduces additional overhead by requiring additional IP addresses and headers to be implemented between the RNC and BTS. In addition, this implementation reduces the overall throughput of data that can be transferred throughout the network. For example, the load balancer can be programmed to increase the wait times to allow fragments to re-join together. However, this increase in time means that less data will actually flow through the network. Less packets that can be transferred from one destination to another results in less revenue for the service provider.
A solution is needed that can allow fragments of packets to flow across multiple T-1 lines or other connections without the need for increased delay times to re-join the fragments. The solution needs to allow the fragments to arrive in sequence at their destination. The solution should solve both the timing (delay) and path (out-of-sequence) issues without the need for additional devices such as the load balancer and re-sequencing timer at the BTS.